1. Field of the Invention
The invention relates to a receiver, and more particularly to a frequency-shift keying receiver.
2. Description of the Related Art
In application of a wireless sensor network, power consumption of sensors at each of network nodes is often a primary consideration, and the wireless transceiver is one of the major factors contributing to power consumption of the sensor.
Referring to FIG. 1, a conventional wireless receiver having direct conversion receiver architecture is shown to include a low noise amplifier (LNA) 11, two mixers 12, an oscillator 13 and two filters 14.
The LNA 11 receives and amplifies a frequency-shift keying (FSK) signal. The oscillator 13 provides two oscillator signals having a phase difference of 90 degrees therebetween. Each of the mixers 12 receives the amplified FSK signal and a respective one of the oscillator signals, and outputs to a respective one of the filters 14 one of an in-phase component and a quadrature component of the amplified FSK signal with a lower frequency by providing a down conversion function for subsequent processing.
However, such conventional architecture requires a stable and precise oscillator 13, resulting in higher difficulty and complexity in circuit design. Division of the FSK signal into the in-phase and quadrature (I/Q) components makes it difficult to reduce circuit elements, thereby resulting in a higher cost and higher power consumption.